Mahla et al. (2025) Variability of heatwave and meteorological features associated with exceptionally hot summer 2022 over Rajasthan, India

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2025
• Date: 2025-10-27
• Authors: Subhkaran Mahla, Radheshyam Sharma, Himanshu Sharma, Jai Prakash, Gajendra Kumar
• DOI: 10.1007/s00704-025-05862-9

Research Groups

• Department of Atmospheric Science, Central University of Rajasthan, Rajasthan, India
• Meteorological Centre Jaipur, India Meteorological Department, Jaipur, India
• Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research, Bhopal, India
• Regional Meteorological Centre New Delhi, India Meteorological Department, New Delhi, India

Short Summary

This study analyzed the spatial and temporal variability of heatwaves (HWs) and associated meteorological features over Rajasthan, India, from 1969 to 2022, revealing a rapid increase in HW frequency and intensity, particularly in western and southeastern regions, with the exceptionally hot summer of 2022 linked to persistent anticyclonic circulation and positive geopotential height anomalies.

Objective

• To analyze the spatial and temporal variability of maximum temperature, extreme temperature, and the frequency and intensity of heatwaves (HWs) over Rajasthan, India, for the period 1969–2022.
• To identify and characterize the meteorological conditions responsible for the exceptionally hot summer of 2022 in the region.

Study Configuration

• Spatial Scale: Rajasthan, India, with a focus on western and southeastern regions and specific districts (e.g., Barmer, Bikaner, Jaisalmer, Sri Ganganagar).
• Temporal Scale: Long-term analysis from 1969 to 2022, with a detailed focus on the pre-monsoon season (March–May, MAM) and the summer of 2022.

Methodology and Data

• Models used: Not applicable (reanalysis data used, not a predictive model).
• Data sources:
  • Daily maximum temperature records from ten India Meteorological Department (IMD) stations across Rajasthan (1969–2022).
  • Daily observed rainfall data from 310 IMD rain gauge stations (MAM 2022).
  • European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis data (0.25° × 0.25° spatial resolution) for monthly averaged wind fields (850, 500, and 250 hPa), 2-meter air temperature, and geopotential height anomalies (1991–2020 climatological means).

Main Results

• A rapid increase in the frequency and intensity of heatwaves (HWs) and severe heatwaves (SHWs) was observed over the past three decades, particularly in western and southeastern Rajasthan.
• The summer of 2022 recorded the highest frequency of HWs and SHW days in the last 54 years, with western districts (Barmer, Bikaner, Jaisalmer, Sri Ganganagar) being most severely affected.
• Summer 2022 was characterized by markedly above-normal maximum temperatures (1.3 °C to 5.7 °C anomalies), intense and prolonged HW spells, and a 66% rainfall deficit.
• A strong association was found between warmer temperature anomalies and anticyclonic wind anomalies at middle and upper tropospheric levels over West Rajasthan.
• Strong southwesterly winds at lower tropospheric levels contributed to warm air advection.
• Positive geopotential height anomalies (60–90 m at middle level, 80–120 m at upper level) over northwest India weakened the subtropical westerly jet, reducing active western disturbances and leading to warmer and drier conditions.
• The first two heatwave spells in March 2022 were associated with strong positive geopotential height anomalies exceeding 90 m at the mid-tropospheric level and 216 m at the upper-tropospheric level.

Contributions

• Enhances the understanding of extreme heatwave conditions and their associated meteorological drivers in northwestern India.
• Provides valuable inputs for improving heatwave early warning systems and disaster risk management.
• Offers practical implications for policy formulation and the agricultural sector, supporting timely advisories for critical harvesting periods.
• Highlights the vulnerability of Rajasthan to climate variability impacts, particularly extreme heat events, due to its arid/semi-arid nature and specific atmospheric circulation patterns.

Funding

• Not explicitly stated beyond acknowledgement of Copernicus Climate Change Service (C3S) for ERA5 reanalysis data.

Citation

@article{Mahla2025Variability,
  author = {Mahla, Subhkaran and Sharma, Radheshyam and Sharma, Himanshu and Prakash, Jai and Kumar, Gajendra},
  title = {Variability of heatwave and meteorological features associated with exceptionally hot summer 2022 over Rajasthan, India},
  journal = {Theoretical and Applied Climatology},
  year = {2025},
  doi = {10.1007/s00704-025-05862-9},
  url = {https://doi.org/10.1007/s00704-025-05862-9}
}